Prior to the present invention, it is well known in today's modern railroad industry that couplers are used to connect adjacently disposed ends of a pair of railway cars together. Further, on any of these railway cars which may possibly be used in interchange type service, these standard couplers must have received approval by the Association of American Railroads (AAR) prior to their being installed on such ends of the railway cars.
It is generally well recognized, in the railroad industry, that such couplers will be required to serve a number of functions in this application. For example, such couplers are used to facilitate the connection and the unconnecting of individual railway cars to and from, respectively, a train consist. Another function served by these couplers is that they enable such individual railway cars to more easily negotiate the curved portion of the track which will be encountered during operation of the train on the track structure. Additionally, such standard couplers perform the function of allowing such railway cars to be easily and readily combined thereby making up a train consist. These standard couplers further permit such adjacent ends of the railway cars to be easily and readily separated into individual cars as necessary for either loading or unloading cargo thereto or therefrom, respectively.
In more recent times, however, in the railroad industry it has come to be generally recognized that a significant number of relatively important advantages can be achieved by the interconnection of a number of railway cars to form a substantially semi-permanent unit. This has been particularly the situation, for example, where such railway cars are specifically designed for use in what is commonly referred to in the railroad industry as "piggyback" or intermodal service. One of the primary reasons for this is that the cargo which is to be either loaded or unloaded is either brought to or removed from, respectively, predetermined central locations. Generally, such central locations are usually owned and operated by the railroads. This cargo is normally either over-the-road trailers or large containers which usually are used to ship cargo by oceangoing vessels.
The individual railway cars which have been connected together in this substantially semi-permanent manner are commonly known in the railroad industry as a "10-pack". Except at the extreme outermost ends of each 10-pack unit, the use of such standard couplers discussed above is not required on these 10-pack units. Because of their dedicated service, these 10-pack units will generally only be broken apart on a periodic basis. This is the primary reason why such standard couplers are not required in this particular application. In most cases, for example, the breaking of these 10-pack units will normally only occur when some maintenance must be carried out on either an individual coupler component or on certain other critical components positioned on the railway car which will require an individual car to be removed from such 10-pack unit on a temporary basis. In the railroad industry, it has become quite obvious that with the use of some type of semi-permanent coupling arrangement it is possible for them to achieve a rather significant reduction in their operating and maintenance costs. These cost reductions can be attributed to a variety of reasons. At a minimum, these reasons include a significant reduction in the weight of the railway equipment. Such weight reduction results in a rather significant reduction in the amount of energy required to move a train consist over the track structure. Because in this semi-permanent coupling arrangement fewer railway trucks are required, there is not only a reduction in equipment costs achieved but this also results in a reduction of the maintenance requirements.
Now, however, with the relatively extensive use of such substantially semi-permanent coupling arrangement, the railroad industry in conjunction with the railway equipment suppliers have determined that it is of critical importance for a close-buttoned relationship to be maintained between the couplers draft components present in a particular coupling arrangement. Further contributing to the importance of this close-buttoned relationship requirement is the ever increasing loads which must be carried by modern railway cars and train consists in order for the railroads to be competitive. This close-buttoned relationship has been found necessary, for example, so that the detrimental effects of the impact forces which are normally encountered during in-track train operation can be reduced to an acceptable level. In this manner, the possible damage that could be incurred by the cargo and/or the railway equipment can be held to an absolute minimum. Such impact forces are generally encountered during normal buff operation of the train consist.
With the above discussion in mind, attention is now directed to a particular prior art type articulated coupling arrangement used for the purpose of connecting adjacent ends of a pair of railway cars together in such semi-permanent fashion. This prior art articulated coupling arrangement is taught in U.S. Pat. No. 4,258,628. As has been illustrated therein, this particular articulated coupling apparatus includes a male connection member and a female connection member. The male connection member is secured at one end thereof to one end of a first railway car body member and the female connection member is secured at one end thereof to an adjacent end of a second railway car body member.
The female connection member, in this prior art coupling arrangement, is rotatably engaged in a center plate bowl portion of the bolster member positioned intermediate the side frames of the railway truck member. Such rotatable-type engagement is accomplished in a manner that is generally well known in the railway art. The outer end portion of the male connection member is disposed for relative movement, at the outer end portion of such female connection member.
A pin member is utilized in this coupling arrangement to connect the outer end portion of the male connection member within the cavity of such female connection member together thereby forming such substantially semi-permanent coupling. This pin member is positioned in a vertical plane. Additionally, this pin member is positioned in aligned apertures which are formed in each of such male connection member and such female connection member. It is of significance to note that, as is taught in this prior art reference, the aperture formed in such male connection member for receiving such pin member therein must be formed somewhat larger than such pin member itself. In this coupling arrangement, this is necessary to permit certain movements that are required of the coupling apparatus during service.
It should additionally be noted that a rear surface portion of such apertures formed in such male connection member and which will receive such pin member therein includes a horizontally disposed concave configuration and a vertically disposed convex configuration. This particular configuration is desirable in this coupling arrangement in order for both the male connection member and the female connection member to be able to move in each of a horizontal direction and a vertical direction with respect to one another. Another substantial area of surface contact between the rear surface of such pin aperture and the pin member itself is provided by this configuration at the same time.
Such male connection member, adjacent the outer end surface of the outer end portion thereof, includes a convex configuration. This convex configuration on the outer end surface of such male connection member abuttingly engages a complimentary concave surface which is formed on a front face portion of a follower member. As illustrated, in this coupling arrangement, this follower member is disposed within the rear portion of such cavity located in the outer end portion of such female connection member. This follower member, on the rear face portion thereof, includes a pair of vertically disposed slot-like cavities formed therein. A first portion of a resilient member is positioned within each of these vertically disposed slot-like cavities. Each such resilient member includes a second portion which extends outwardly from the rear face portion of such follower member. In this manner, a vertically disposed wedge-like element can be engaged with the exposed outermost surface area of each such resilient element. Such wedge-like element being a necessary component so that during service of this coupling arrangement such follower member and the male connection member can be urged forwardly. Consequently, the rear surface portion of the aperture formed in such outer end portion of the male connection member will be maintained substantially in mating engagement with such pin member at all times. In this coupling arrangement, because the majority of the articulated connecting members used are normally manufactured as cast components, such mating engagement being maintained between such pin members and the rear surface portion of this aperture disposed in the male connection member is essential. Furthermore, in attempting to maintain the manufacturing costs of this coupling arrangement as low as possible, such cast connecting components will normally receive very little, if any, finish machining necessary to provide either the required or the desirable dimensional control. In other words, these cast connecting members will generally be used as cast. As a result of this manufacturing cost-saving practice, it is quite often difficult to provide an articulated coupling apparatus that will be self-adjusting under the various wear conditions which such coupling apparatus will normally be subjected to during operation. It is important, nevertheless, to minimize as much as possible the slack encountered in the various coupling connections during such in track service.
Other prior art type coupling devices are taught in U.S. Pat. No. 3,716,148 and Canadian Patent Number 1,231,078.